1. Field of the Invention
Embodiments of the present invention relate to a phosphor for emitting yellow light, a method for producing the phosphor and a light emitting device.
2. Description of Related Art
Phosphor powders are used, for example, for light emitting devices such as light emitting diodes (LEDs). Light emitting devices comprise, for example, a semiconductor light emitting element which is arranged on a substrate and emits light of a pre-determined color, and a light emitting portion containing a phosphor powder in a cured transparent resin, that is, an encapsulating resin. The phosphor powder contained in the light emitting portion emits visible light by being excited by ultraviolet light or blue light emitted from the semiconductor light emitting element.
Examples of the semiconductor light emitting element used in a light emitting device include GaN, InGaN, AlGaN and InGaAlP. Examples of the phosphor of the phosphor powder used include a blue phosphor, a green phosphor, a yellow phosphor and a red phosphor, which emit blue light, green light, yellow light and red light, respectively, by being excited by the light emitted from the semiconductor light emitting element.
In light emitting devices, the color of the radiation light (emitted light) can be adjusted by including various phosphor powders such as a yellow phosphor in an encapsulating resin. More specifically, using in combination a semiconductor light emitting element and a phosphor powder which absorbs light emitted from the semiconductor light emitting element and emits light of a predetermined wavelength range causes action between the light emitted from the semiconductor light emitting element and the light emitted from the phosphor powder, and the action enables emission of light of a visible light region or white light.
In the past, a phosphor containing strontium and having a cerium-activated sialon (Si—Al—O—N) structure (Sr sialon phosphor) has been known.